Patterning and formation of copper electroplated contact for bifacial silicon hetero-junction solar cell

In this work, tungsten doped indium oxide (IWO) film was deposited as anti-reflection coating and conductive layer for silicon hetero-junction (SHJ) solar cell, which meant the necessity to mask the pattern of grid electrodes for selective plating. We investigated the plating process and compared three different masking resists suitable for large area SHJ solar cells. The results revealed that light-sensitive dry film was appropriate as plating resist due to its simple process, high resolution and rectangular shape. As a proof of concept, copper plated SHJ solar cell with an efficiency of 22% was fabricated in SIMIT's R&D line. Compared with screen printed finger, copper plated finger showed narrow width, higher aspect ratio and lower bulk resistivity, leading to decreased shading loss without increasing girds power loss. The metallization refinement contributed 2.80% of power loss reduction, which indicated the possibility to achieve higher efficiency by copper metallization after well optimization.